Eddy-current artifact reduction in balanced steady-state free precession magnetic resonance imaging
AssigneeUniversity of Southern California
InventorsJon-Fredrik Nielsen, Krishna S. Nayak
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Abstract
Magnetic resonance imaging techniques are described that utilize bSSFP sequences in which two or more gradient waveforms are interleaved in a “groupwise” fashion, i.e., each waveform is executed consecutively two or more times before switching to the other waveform, where “N” counts the number of times each waveform is executed consecutively. As a result, embodiments of the present disclosure can mitigate steady-state signal distortions or artifacts in interleaved balanced steady-state free precession (bSSFP) caused by slightly unbalanced eddy-current fields. Related MRI systems are also described.
Claims17
A method of artifact reduction using gradient waveform grouping for balanced SSFP imaging, the method comprising:
- with a MRI system, providing a balanced steady state free precession (SSFP) pulse sequence of RF pulses and balanced gradient pulses to an object;
- interleaving two different gradient waveforms of the SSFP pulse sequence;
- switching between from a first of the two different gradient waveforms to the second gradient waveform after a number of N repetitions, where N>2;
- and
- imaging the object with the MRI system.
A MRI system for generating MRI images of an object, the MRI system comprising:
- a static field generator configured to generate a static magnetic field B0;
- a gradient field generator configured to generate a time-varying gradient field G(r), parallel to B0;
- and
- an RF excitation pulse generator configured to generate an RF excitation field B1 and apply the field B1 to the object so that nuclear spins in the object flip at a flip angle;
- and
- a balanced SSFP pulse sequence of RF and gradient pulses, wherein the SSFP pulse sequence includes two interleaved different gradient waveforms that are alternated after a number of N repetitions, where N>2;
- and
- an image processing system configured and arranged to display images of the object.
An MRI controller system for a magnetic resonance imaging (MRI) system, the system comprising:
- a controller configured and arranged to (i) control an RF excitation pulse generator and gradient field generator to produce a balanced steady state free precession (SSFP) pulse sequence, (ii) interleave two different gradient waveforms of the SSFP pulse sequence, (iii) switch between a first of the two different gradient waveforms to the second gradient waveform after a number of N repetitions, where N >2, (iv) image an object with the MRI system.
Dependencies are inferred from the claim text.